
#ifndef __ui_gfx_png_codec_h__
#define __ui_gfx_png_codec_h__

#pragma once

#include <vector>

#include "base/basic_types.h"

class SkBitmap;

namespace gfx
{

    class Size;

    // Interface for encoding and decoding PNG data. This is a wrapper around
    // libpng, which has an inconvenient interface for callers. This is currently
    // designed for use in tests only (where we control the files), so the handling
    // isn't as robust as would be required for a browser (see Decode() for more).
    // WebKit has its own more complicated PNG decoder which handles, among other
    // things, partially downloaded data.
    class PNGCodec
    {
    public:
        enum ColorFormat
        {
            // 3 bytes per pixel (packed), in RGB order regardless of endianness.
            // This is the native JPEG format.
            FORMAT_RGB,

            // 4 bytes per pixel, in RGBA order in memory regardless of endianness.
            FORMAT_RGBA,

            // 4 bytes per pixel, in BGRA order in memory regardless of endianness.
            // This is the default Windows DIB order.
            FORMAT_BGRA,

            // 4 bytes per pixel, in pre-multiplied kARGB_8888_Config format. For use
            // with directly writing to a skia bitmap.
            FORMAT_SkBitmap
        };

        // Represents a comment in the tEXt ancillary chunk of the png.
        struct Comment
        {
            Comment(const std::string& k, const std::string& t);
            ~Comment();

            std::string key;
            std::string text;
        };

        // Calls PNGCodec::EncodeWithCompressionLevel with the default compression
        // level.
        static bool Encode(const unsigned char* input,
            ColorFormat format,
            const Size& size,
            int row_byte_width,
            bool discard_transparency,
            const std::vector<Comment>& comments,
            std::vector<unsigned char>* output);

        // Encodes the given raw 'input' data, with each pixel being represented as
        // given in 'format'. The encoded PNG data will be written into the supplied
        // vector and true will be returned on success. On failure (false), the
        // contents of the output buffer are undefined.
        //
        // When writing alpha values, the input colors are assumed to be post
        // multiplied.
        //
        // size: dimensions of the image
        // row_byte_width: the width in bytes of each row. This may be greater than
        //   w * bytes_per_pixel if there is extra padding at the end of each row
        //   (often, each row is padded to the next machine word).
        // discard_transparency: when true, and when the input data format includes
        //   alpha values, these alpha values will be discarded and only RGB will be
        //   written to the resulting file. Otherwise, alpha values in the input
        //   will be preserved.
        // comments: comments to be written in the png's metadata.
        // compression_level: An integer between -1 and 9, corresponding to zlib's
        //   compression levels. -1 is the default.
        static bool EncodeWithCompressionLevel(const unsigned char* input,
            ColorFormat format,
            const Size& size,
            int row_byte_width,
            bool discard_transparency,
            const std::vector<Comment>& comments,
            int compression_level,
            std::vector<unsigned char>* output);

        // Call PNGCodec::Encode on the supplied SkBitmap |input|, which is assumed
        // to be BGRA, 32 bits per pixel. The params |discard_transparency| and
        // |output| are passed directly to Encode; refer to Encode for more
        // information. During the call, an SkAutoLockPixels lock is held on |input|.
        static bool EncodeBGRASkBitmap(const SkBitmap& input,
            bool discard_transparency, std::vector<unsigned char>* output);

        // Decodes the PNG data contained in input of length input_size. The
        // decoded data will be placed in *output with the dimensions in *w and *h
        // on success (returns true). This data will be written in the 'format'
        // format. On failure, the values of these output variables are undefined.
        //
        // This function may not support all PNG types, and it hasn't been tested
        // with a large number of images, so assume a new format may not work. It's
        // really designed to be able to read in something written by Encode() above.
        static bool Decode(const unsigned char* input, size_t input_size,
            ColorFormat format, std::vector<unsigned char>* output, int* w, int* h);

        // Decodes the PNG data directly into the passed in SkBitmap. This is
        // significantly faster than the vector<unsigned char> version of Decode()
        // above when dealing with PNG files that are >500K, which a lot of theme
        // images are. (There are a lot of themes that have a NTP image of about ~1
        // megabyte, and those require a 7-10 megabyte side buffer.)
        //
        // Returns true if data is non-null and can be decoded as a png, false
        // otherwise.
        static bool Decode(const unsigned char* input, size_t input_size,
            SkBitmap* bitmap);

        // Create a SkBitmap from a decoded BGRA DIB. The caller owns the returned
        // SkBitmap.
        static SkBitmap* CreateSkBitmapFromBGRAFormat(
            std::vector<unsigned char>& bgra, int width, int height);

    private:
        DISALLOW_COPY_AND_ASSIGN(PNGCodec);
    };

} //namespace gfx

#endif //__ui_gfx_png_codec_h__